Rotary displacement machine

ABSTRACT

Rotary fluid displacement machine having a housing with a cylindrical cavity in which a rotor is journaled and wherein the rotor has end plates with axially inwardly extending undulating projections which extend into grooves in the housing. Sliding blocks are provided in bores in the housing and at their ends engage said undulating surfaces to form working chambers with alternating ones of the working chambers at each side of the housing at a higher fluid pressure and the others thereof at a lower fluid pressure at any instant, and sliding seal elements sealing against leakage of fluid from the working chambers to the outside between the rotor and housing and between working chambers toward the inside of the housing.

llited States tet [72] inventors Robert Rudolf Prescher;

Werner Schroder. both of Essen, Germany 1211 Appl. No 825,745

[54] ROTARY DISPLACEMENT MACHINE 29 Claims, 29 Drawing Figs.

521 U.S.Cl 418/139 511 rm.c| ..F01c19/00 103/139;

[50] Field ofSearch...-.

, 123/16A,8SS; 230/152 [56] References Cited UNITED STATES PATENTS 3,163,090 12/1964 Conrad... 123/16 A 3,205,663 103/139 9/1965 Kluge Primary Examiner-C. .l. Husar Attorney-Walter Becker ABSTRACT: Rotary fluid displacement machine having a housing with a cylindrical cavity in which a rotor is journaled and wherein the rotor has end plates with axially inwardly extending undulating projections which extend into grooves in the housing. Sliding blocks are provided in bores in the housing and at their ends engage said undulating surfaces to form working chambers with alternating ones of the working chambers at each side of the housing at a higher fluid pressure and the others thereof at a lower fluid pressure at any instant, and sliding seal elements sealing against leakage of fluid from the working chambers to the outside between the rotor and housing and between working chambers toward the inside of the housing.

PATENTED JUNE? IQYI SHEET 03 0F PATENTED JUH22 197:

SHEET 08 0F PATENTEDJUNZZIQYI 3588467 SHEET BMW 11 PATENTEU JUN22|971 3,586,467

' sum as or 11 PATENIEU JUNE? 1921 sum in HF 5 ER Q ROTARY DISPLACEMENT MACHINE The present invention relates to a rotary displacement machine which comprises an annular housing and a rotor which if formed by a cylinder joumaled in the annular opening of the housing and by two discs which at both sides of the housing between the end faces thereof and equidistant undulated annular surfaces define annular passages. These annular passages are by means of sliding blocks axially displaceable in recesses of said housing divided into working chambers communicating with sources of different fluid pressure in such a way that in each two working chambers which at the circumference of each annular passage follow each other and in each two working chambers located opposite to each other at both sides of the housing there prevail liquid pressures of different working phases. Furthermore, sliding rings are provided which prevent the pressure fluid from passing from any working chamber through gaps between the housing and the runner toward the outside or toward a working chamber located opposite with regard to'said housing. Such rotary displacement machine has been described for instance in U.S. Pat. No. 3,279,392. According to the devices described in the said U.S. patent, sliding rings are employed which are elastically deformable in radial direction and are closed in themselves.

In contrast thereto, it is an object of the present invention, with a rotary displacement machine of the above mentioned general type so to seal the housing and the rotor with regard to each other that the seal will be particularly nonsensitive against thermal influences and against an elastic deformation.

It is another object of this invention to provide a rotary displacement machine as set forth in the preceding paragraph which will be subjected only to a relatively low wear and can be easily mounted.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIG. 1 represents an axial section through a rotary displacement machine, said section being taken along the line H of FIG. 3.

FIG. 2 shows the developments a, b and c into the drawing plane of a section taken along the line Ila-Ila, IIb-Ilb and lIc-I- Ic respectively in FIG. I and also diagrammatically shows an axial section through two enclosed stroke displacement machines.

FIG. 3 is a section taken along the line Ill-III of FIG. 1.

FIG. 4 represents a section along the line lV-IV of FIG. 3 and FIG. 5. 7

FIG. 5 illustrates a view as seen in the direction of the arrow V of FIG. 4.

FIG. 6 represents a section along the line VI-VI of FIG. 3.

FIG. 7 shows a section along the line VII-VII of FIG. 3.

FIG. 8 represents a section along the line VIIIVIII of FIG. 3.

FIG. 9 illustrates a view as seen in the direction of the arrow IX of FIG. 8 (and FIG. 10).

FIG. 10 is a view as seen in the direction of the arrow X of FIG. 9.

FIGS. I1, 13 and 15 respectively illustrate sections according to the lines Xl-XI, XIIIXIII and XV-XV of FIG. 3.

FIG. I2 represents a section taken along the line XII-XII of FIG. 11.

FIG. 14 represents a section along the line XIV-XIV of FIG. 13.

FIG. 16 is a section along the line XVI-XVI of FIG. 15.

FIG. 17 is a top view along the line XVII-XVII of FIG. 16.

FIG. 18 is an isometric view shows a portion of the housing with a sealing strip combination.

FIG. I9 is a view similar to that of FIG. 18 after elimination of a bushing partially shown in FIG. [8.

FIG. 20 illustrates a section similar to that of FIG. 7 and shows a modified arrangement according to the invention.

FIG. 21 is a view as seen in the direction of the arrow XXI in FIG. 20.

FIGS. 22 and 23 respectively illustrate an explosive view of the construction shown in FIGS. 20 and 21.

FIGS. 24 is a top view as seen in the direction of the arrow XXIV of FIG. 20.

FIG. 25 shows a portion of a sealing strip combination in a section which corresponds to that of FIG. 11.

FIG. 26 represents a section along the line XXVI-XXVI of FIG. 25.

FIGS. 27 and 28 show sections for other adjustments of the sealing strip, these sections corresponding to those of FIGS. 25 and 26.

FIG. 29 is an isometric view of a portion of the housing with a sealing strip combination, according to which the annular segments in contrast to the embodiment of FIGS. 3 and 11- 19, for effecting a sealing between the working chambers on different sides of the housing.

The invention is characterized primarily in that the sliding rings are subdivided in ring elements each of which extends from the radial central plane of a sliding block in tangential direction nearly over half the working chambers on both sides of the sliding block, and is furthermore characterized in that the gap between the ends of each two annular segments are bridged in a sealing manner by cover elements.

Advantageously, each annular segment is located in grooves which are arranged at the end faces of the housing, with play at the circumference and in the back, and this play in interrupted by an angle member within the area of the pertaining sliding block. The said angle member rests by means of two cylindrical sealing surfaces on the circumference of the annular segments or on the inner cylindrical confining surface of the groove. The said angle member furthermore has plane sealing surfaces one of which engages the back surface of the annular segment while the other is in alignment with the end face of the annular segment.

Preferably, the annular segments serving for sealing toward the outside rest on both sides of the housing on cylindrical surfaces of the discs which have the same diameter as the outer circumference of the annular passages forming the working chambers and which form the inner cylindrical confining surface of the grooves receiving said annular segments. Each outwardly sealing annular segment is preferably prevented by a nose from displacing itself in tangential direction. This nose, within the region of a sliding block engages the groove in the housing.

When employing bushings inwhich the sliding blocks provided with cylindrical sliding surfaces are axially displaceably guided, the bushings are preferably at the end faces thereof provided with extensions the end faces of which do not serve as sealing surfaces. The said extensions are provided with slots which have a central plane common with the sliding blocks and extending through the axis of rotation. In each slot there is guided the rail on which the sliding strip of the pertaining sliding block slides in axial direction and there is also guided a .sealing member which forms a further element of a sealing strip combination.

For purposes of initially pressing the annular segments against the cylindrical surfaces of the rotor discs, there are provided, for instance, spring means which are adapted to act upon the cover members and the angle members. Further spring means serving for initially pressing the annular seg ments against the cylindrical surfaces of the discs may be provided within the region between the cover members and the angle members.

Each outwardly sealing annular segment is advantageously on its inside provided with flat pockets in such an arrangement that at least an annularly closed narrow supporting surface as well as supporting surfaces between the pockets are formed. In this way, the sliding friction will be reduced. Furthermore, each annular segment may have its inside provided with flap recesses which are open toward the end face. In these flat recesses, worn particles will collect which originate from the driving mechanism and can easily be washed out of the pockets.

Also for effecting a sealing between the working chambers on different sides of the housing there are provided sliding ring segments. In this way, the housing is saved against undue load acting in radial direction, which load would occur when the high oil pressure acting in the working chambers were about to be conveyed into the annular gap between the cylinder of the rotor journaled in the annular opening of the housing and the housing. The grooves for these inner annular segments preferably have a radius of curvature which is greater than the distance between the grooves in the central planes of the sliding block, said planes passing through said axis of rotation, and the axis of rotation. This brings about that the surfaces which in axial direction are acted upon by the high liquid pressure in the interior of the rotary displacement machine are reduced to a minimum so that the screws which have to absorb these axial forces and by means of which the rotor discs are tightened to the cylinder will not be subjected to too high stresses. On the other hand, by means of such eccentric arrangement of the inner annular segments, it will be prevented that these annular segments dig into the counter forces of the rotating discs.

Advantageously, provisions are made by means of which movable elements of the employed sealing strip combination prior to the assembly of the rotary displacement machine are so held in the respective grooves that they cannot be pressed out of the grooves by the springs which in operation exert the initial pressure upon the annular segments. This greatly facilitates the assembly. Advantageously, a corresponding sealing strip, which may for instance be of an angleshaped contour acted upon by a spring in radial direction and a stronger spring in axial direction comprises an inclined groove which has an engaging surface for a pin, said engaging surface extending substantially at a right angle with regard to the resultant of the two spring forces. The said pin extends into the groove for limiting the displacement of the sealing strip. The said pin may be formed for instance by the leg of a resilient wire yoke.

Referring now to the drawings in detail and as shown primarily in FIGS. ll, 2 and 3, the rotary displacement machine comprises an annular housing 1 and a rotor. The rotor comprises a cylindrical center member 2 which within the annular opening of the housing 1 is by means of inserted bearing rings 3 at the end faces of said central member rotatably journaled. The said rotor furthermore comprises two discs 4 which confine the housing 1 at the end faces thereof. The central member 2 and the discs 43 are held together by anchor screws 44:. The housing 1 comprises at both sides two annular passages 6 (FIG. 2) which are coaxial with regard to the axis of rotation 5. The discs 4 are provided with annular beads, enlargements, or wavy annular projections 7 which extend into the annular passages 6 and which at the end faces are provided with closure surfaces 8, 9 which when viewed in the development of FIG. 2 have a wave-shaped profile. The closure surfaces 8, 9 have two wave crests which extend almost to the end faces of the housing, and therebetween two valleys each which are so arranged that each point of one closure surface has the same distance from the axially oppositely located point of the other closure surface 9.

The two annular passages 6 are each subdivided into four working chambers 10, 11, 12, 13; M, 15, 16, 17 by means of cylindrical sliding blocks l which are displaceably guided parallel to the axis of rotation in bushings 19 which are fixedly located in the housing 1. Each sliding block 18 has both of its ends provided with radially extending slots 20 (FIG. 2) in which at the end faces there are slidably and fittingly guided sealing strips 21 which under the action of nonillustrated springs and under the action of the liquid pressure protrude almost in axial direction from the slots 20 and along lines extending radially with regard to the axis of rotation 5 engage the closure surfaces 8, 9. The sealing strips 21 are at their upper and lower ends angled off in the direction toward the center of the sliding block. The thus formed legs have their upper and lower sides provided with sealing surfaces 22 which are in alignment with the cylindrical outer and inner circumferential surfaces 23, 24 respectively of the annular beads 7. Central sealing strips 25 (FIG. 1) extend in axial grooves of the sliding blocks 18 on the upper and lower sides thereof between the sealing strips 21 at the end faces. These sealing strips 25 serve for sealing the sliding blocks 18 relative to the sliding bushings l9 and for securing the location of said sliding blocks 18 relative to said bushings 19.

As will be evident from FIG. 2, on one side of housing 1, two working chambers 10 and 12 which are offset with regard to each other by and the working chambers 15 and 17 which are offset relative to the chambers 10 and 12 by communicate with the cylinder 28 of a stroke displacer through passages 26 in the housing 1. The piston 29 in cylinder 28 of the stroke displacer is connected by a piston rod to the piston 30 of an internal combustion engine.

The other working chambers 11 and 13 and M and 16 on both sides of the housing are connected with the cylinder 33 of a further stroke displacer through passage 31 in housing 1 and a conduit 32. The piston 34 in cylinder 33 of said stroke displacer is connected by a piston rod to the piston 35 of the internal combustion engine.

FIG. 2 illustrates a working phase according to which the piston 34 of one stroke displacer occupies its intermediate downward position, and in which in view of the explosion pressure acting upon the piston 35 oil is pressed into the working chambers 11, 13, 14 and 16. At the same time, oil is pressed from the working chambers 10, 12, 15 and 17 underneath the piston 29 of the other stroke displacer which occupies its intermediate upward position and brings about that the piston 30 presses the exhaust gases of the preceding combustion phase out of the pertaining cylinder. Under the influence of the oil pressure prevailing in the working chambers 11, 13, 14 and 16, a torque is exerted upon the discs 4 in the direction of the arrows P shown in FIG. 2 so that the rotor 2, 4 is turned.

After each turning movement of the rotor by 90, which means after each single stroke of the pistons 29 and 2.4, the conditions change in such a way that oil is pressed into the working chambers from which previously oil was pressed out, and vice versa. Consequently, on each side of the housing in two succeeding working chambers for instance llll and 12 and in two working chambers located opposite to each other for instance chambers 11 and 15, oil pressures of different working phases prevail. The oil pressure in the working chambers varies between a peak of almost 200 kp per square centimeter and 10 kp per square centimeter.

In view of the therefore high pressure differences which alternately may exist between two working chambers on the same side of the housing and between two working chambers on different sides of the housing, effective and reliable provisions have been made for obtaining a proper seal. In particular, the following sealing areas are to be noted:

a. Those gaps which communicate with the atmosphere and are located between the housing 1 and the cylindrical outer circumferential surfaces 23 of the discs 4areas a in FIG. 1.

b. The gap between the housing 1 with the sliding block bushings 19 arranged therein and the cylindrical outer circumferential surfaces 23 of the annular heads 7 as well as the circumferential surfaces of the sliding blocks 18- areas bin FIG. 1.

c. The gap between the wave-shaped closure surfaces 8, 9 of the annular beads 7 and the end faces of the sliding blocks 18-areas c in FIG. 1.

d. The gaps between the housing 1 with the sliding bushings 19 therein and the cylindrical inner circumferential surfaces 24 of the annular beads 7 and with the circumferential surfaces of the sliding blocks 18-areas C in FIG. 1.

e. The gaps between the housing l with the sliding bushings 19 therein and the engaging surfaces of the discs 4-areas d in FIG. 1.

f. The gaps between the housing I, the bearing rings 3 therein and the end faces of the discs 4areas e in FIG. 1.

For purposes of sealing the gaps at a, on each side of the housing there are provided four slide ring segments 36 which rest on the outer cylindrical circumferential surfaces 23 of the discs 4 and thus extend over a quarter of the circumference of these surfaces. On one hand, they have each a cylindrical sealing surface 37 (FIG. 7) which rests on the cylindrical circumferential surface 23. On the other hand, the sliding ring segments 36 are at their outer end faces provided with vertical sealing surfaces 38 by means of which they engage vertical surfaces of rings 39 which by means of screws 40 are connected to the housing 1 and the cylindrical inner surfaces of which together with the outer cylindrical circumferential surfaces 23 of the discs 4 form a narrow gap. Between the ends of each two successive sliding ring segments 36 there is provided a small gap 41 (FIG. 5). The gaps 41 are bridged by cover members 42. These members 42, as indicated in FIGS. 4 and 5, have an angle-shaped profile. Each cover member 42 in its turn rests along a plane sealing surface 43 in a sealing manner on plane surfaces at the bottom of recesses 44 in the ends of the slide ring segment 36. Furthermore, the leg of each cover member 42 which extends behind the backs of the slide ring segments 36 rests by means of a cylindrical sealing surface 45 on the cylindrical outer circumferential surface 23 of the respective disc 4 in a sealing manner. In axial direction, each cover member 42 sealingly engages the respective ring 39 by means of a vertical sealing surface 46 which is in alignment with the vertical sealing surfaces 38 of the slide ring segments. Furthermore, each cover member 42 by means of vertical sealing surface 47 rests on the back surfaces of the slide ring segments 36. In this way, the gap 41 is sealed in all directions. The pressing of the cover member 42 against the counter surfaces in efi'ected on one hand by the liquid pressure which acts through the gap (in the lower part of FIG. I and in FIG. 4 designated with the letter g) between the housing 1 and the annular beads 7 and is conveyed from the working chambers, for instance 10, to the cover members 42 and the slide ring segments 36. In this way, also the annular segments are pressed against the counter surfaces.

This pressure in radial direction is aided by leaf springs 48 which are located in recesses of the cover members 42 and rest against housing 1. On the other hand, similar leaf springs 49 are provided at areas between the ends and the centers of the slide ring segments, see in particular FIG. 6. Further cor responding leaf springs 50 are, as is shown in particular in FIG. 7, provided in the sealing strip combination (to be described further below) in the central portions of the sliding ring segments.

The slide ring segments 36 do not with their entire cylindrical inner surface 37 rest on the outer circumferential surfaces 23 of the annular beads, enlargements, or wavy annular projections 7 of discs 4 but rest only with a narrow annular surface 51 (FIG. 9) upon the outer marginal area of each sliding ring segment and with narrow web surfaces 52 extending transverse thereto. Therebetween are provided flat recesses 53. These recesses communicate through bores 54 with the gap on that side of the annular segment 36 which faces away from the outer circumferential surface 23.

The narrow annular surface 51 of each ring segment is within the area of the narrow web surfaces 52 interrupted by small wiper pockets 55 which are open toward the outside. It is in these pockets that minute worn particles collect which are fonned during the sliding of the discs 4 on the sliding ring segments and which from these pockets 55 are washed outwardly over the shortest path. Mounted on the slide ring segments 36 are strips 56 which extend into the gap between the discs 4 and the rings 39.

The slide ring segments 36 are prevented from taking part in the rotary movement of the discs 4. To this end, said segments 36 are provided with noses 57 milled out from the central por tion thereof, and these noses extend into recesses which are located in axial extensions 58 of the slide block bushings I9. (FIG. 3)

In order to prevent that in the central areas of the slide ring segments 36, in other words, within the area of the sliding blocks 18, oil passes through the gaps located in the back of the slide ring segments from one working chamber to the adjacent working chamber, the following sealing strip combination has been provided.

As is shown in particular in FIG. 7, within the said regions angle members 59 extend over the annular segments 36 and, more specifically, over the noses 57. These angle members 59 continue in axial direction to form sealing strips 60. The members 59 on one hand by means of a plane sealing surface 61 rest on the outer surface of the respective nose 57 and on the other hand by means of a cylindrical inner sealing surface 62 rest on the outer circumferential surface 23 of the annular beads, enlargements, or wavy annular projections 7 and also rest in a sealing manner on the sealing surface 22 of the axial legs of the sealing strips 21. On the other hand, the angle members 59 by means of sealing surfaces 63 which are in alignment with the vertical sealing surface 38 of the slide ring segments, rests in a sealing manner against the rings 39. Furthermore, the angle members 59 by means of vertical sealing surfaces 64 rests against the back surfaces of the slide ring segments 36 likewise in a sealing manner.

Furthermore, the angle members 59 are by means of the adjacent sealing strips 60 guided in slotlike recesses 65 (FIG. 22) of the slide ring bushings l9 and the extensions 58 thereof in such a manner that by means of their side surfaces they rest sealingly against the radially extending inner surfaces of the recesses 65. In view of this sealing strip combination, it will be assured that when the sliding block 18 is displaced, which displacement is inherent to a sliding of the sealing surfaces 22 of the end faces of the sealing strips 21 on the sealing surfaces 62 of the sealing strips 60, no oil can pass from a working chamber to the adjacent working chamber or toward the outside. The sealings are those in the areas b (FIG. I).

With the described construction, it is, however, also assumed that the extensions 58 of the sliding block bushing 19 by means of their end faces sealingly engage the rings 39, in other words are precisely in alignment with the abutment surfaces 66 of the housing I on the end faces thereof and with the vertical sealing surfaces 38 and 63 of the sliding ring segments 36 and of the angle members 59. According to a further step in conformity with the invention as illustrated in FIGS. 20- 24, the said requirement is not necessary. Therefore, in such an instance, it is not necessary to adapt the length of the sliding block bushings 19 with the extensions 58 to the length of the bores in the housing I which receive the same. As a matter of fact, with the embodiment of FIGS. 20-24, the extensions 58 of the sliding block bushings 19 are slightly shorter than the bores in housing 1 receiving same so that, as evident from FIG. 20, between the end faces of the extensions 58 and the rings 39 gaps 67 are obtained. Therefore, it is not necessary that the bushings 19 are produced with the otherwise required high precision as to the length thereof or have to be installed with an overlength which has to be taken off during the assembly, which causes high manufacturing and assembly costs and increases the danger of waste.

In order to assure that nevertheless the required seal will be assured in all directions, according to the embodiment of FIGS. 20-24, the sealing combination is employed in the areas of the sliding blocks which means in the central region of the sliding ring segments 36, by means of a further simple sealing element in the form of a yoke 68. This member 68 by means of two legs 69 extends over the angle member 59 in such a way that by means of a vertical sealing surface 70 which is in alignment with the vertical sealing surfaces 38 and 63 of the sliding ring segment 36 and the angle member 59, engages the ring 39. One leg'69 is guided in a recess 71 of the angle member 59 toward three sides in radial direction and in a sealing manner. The other leg 69 engages by means of a vertical sealing surface 72 the back surface of the angle member 59. The central portion of the yoke 68 has its sealing surface 73 in engagement with the inner surface 74 which is freed by the slotlike recess 65 and pertains to the bore of the housing 1 which receives the sliding block bushing 19. The central portion of the yoke 68 is held in engagement with the surface 74 by means of a radially acting leaf spring 75 which is located in a recess provided in the angle member 59. The space between the angle member 59 and the intermediate portion of the yoke 68 is in communication with the slotlike recess 65 through a bore 76 (FIG. 20) so that the liquid pressure prevailing therein aids the force of the leaf spring 75 which acts in radial direction outwardly upon the yoke 68.

In axial direction, the yoke 68 acts upon a helical spring 77 which is located in a bore of the extension 58. Spring 77 together with the liquid pressure prevailing in the slotlike recess 65 brings about that the member 68, the angle member 59, and the slide ring segment 36 with the vertical sealing surfaces 70, 63, 38 engage the counter surface of the ring 39.

Since, in each instance the sliding ring segments 36 rest on the outer circumferential surface 23 the diameter of which does not exceed the radial distance of the outer circumference of the chambers lll7 from the axis of rotation 5, it will be brought about that the surface acted upon in axial direction by the high oil pressure in the working chambers will have a minimum outer diameter so that the respective hydrostatic force which in axial direction acts upon the discs 4, which force has to be absorbed by the bolts 40, will be limited to a minimum.

The seal between the areas indicated in FIG. 1 with e is effected by means of four slide ring segments 78. These segments are located in circular grooves 79 which are located in the bearing rings 3 on the end faces thereof. It is advantageous to make the radius of curvature of these grooves considerably greater than the distance between the grooves in the radial central plane 80 of the sliding blocks 18 from the axis of rotation 5. As a result thereof, the region of the surfaces of discs 4 which is delimited by the slide ring segments 78 toward the inside, said discsbeing subjected temporarily to high oil pressure in the working chambers in axial direction, is limited to a minimum. In this connection, attention is directed to the sickle-shaped surfaces 81 in FIG. 3. Furthermore, the eccentric arrangement of the slide ring segments 78 brings about that the axial pressures between these annular segments and the end faces 90 of the discs 41 are distributed in radial direction over a considerable area. In this way, the ring segments are prevented from digging into the surfaces 90..

Between each two successive sliding ring segment 78 there is provided a gap 82 (FIGS. 3, 16 and 17). These gaps 82 are bridged by cover members 83 which are axially displaceably guided in recesses 84 of the bearing rings 3. The said segments 78' by means of sliding surfaces 85 and bearing surfaces 86 tightly engage corresponding surfaces of the recesses 84 and are secured against being lifted out of the recesses 84 by strips 87 which slide in the grooves of the recesses. Two helical springs 88 are located in bores of the cover members 83 and rest against the rear walls of the recesses 84. The outer end faces 89 of each cover plate 33 are by means of the springs 88 tightly pressed against a vertical end face 90 of the respective disc 4. However, the surface 89 is relieved and extensions 91 on the ends of slide ring segments 78 extend into notches 93 in the outer end faces of members 83. These segments 78 engage by means of vertical sealing surfaces 92 the end face 90 of the disc 4 in a sealing manner. Furthermore, care has been taken that extensions 91 on the ends of segments 78 will in tight gaps 93 in the end of cover member 83 sealingly engage the pertaining cover member 83. Therefore, there will be obtained a sealing surface which extends in an uninterrupted manner over the entire circumference between the bearing rings 3 and the rotating disc 4.

Within the area of the radial central planes 80 of the sliding blocks 18, the seal on all sides with the sealing strip combination brought out in FIGS. 11, 12, 19 and 18 is effected. The areas involved are those indicated in FIG. 1 with c and d.

Thus, on each sliding block bushing 19, on that side which faces the axis of rotation there is provided an extension 94 which extends into a hollow 95 of the respective bearing ring 3 and the adjacent part of the housing 1 and which forms a cylindrical confining surface of the working chambers 10-17 and consequently also coincides with the cylindrical circumferential surface of the bearing ring 3. Between each extension 94 and the grooving of the bearing ring 3 there is provided a play 97 (FIGS. 12 and 18). Between the end face 98 of each extension 94 and the end face 99 of the bearing rind 3 on one hand and the end face 90 of the disc 4 on the other hand there is a gap 100 (FIG. 11). The sealing strip combination employed for bridging this gap has an angle member 101 which by means of cylindrical inner surfaces 102 and 103 rests in a sealing manner on the outer circumferential surface of the sliding ring segment 78 and on the-cylindrical surface 104 of grooves 79. Furthermore, the vertical sealing surface 103 which pertains to the angle member 101 and is in alignment with the vertical sealing surface 92 of the slide ring segment 78 engages the end face 90 of the disc 4. Furthermore, the angle member 101 has its vertical sealing member 106 in sealing engagement with the back surface of the sliding ring segments 7.

Located behind the angle member 101 in spaced relationship thereto there is stationarily located in the bearing ring 3 a supporting member 107 with a cylindrically curved sealing surface 108 which sealingly engages the circumferential surface 109 of the extension 94 and thus bridges the gap 97 (FIG. 12).

Journaled on the angle member 101 is a sealing surface 109 of a further angle member 110 which by means of a sealing surface 111 sealingly engages the end face 90 of the disc 4, said sealing surface 111 being in alignment with the sealing surfaces and 92 of the angle member 101 and the slide ring segment 78 respectively. Between the angle member and a further sliding member 111 in alignment therewith there is sealingly engaging the short leg 112 of an angle-shaped sealing strip 1 13 the longer leg of which by means of a sealing surface 114 sealingly engages the cylindrical inner circumferential surface 24 of the respective annular bead, enlargement, or wavy annular projection 7. Furthermore, the sealing surface 114, as will be evident from FIG. 11 sealingly engages the surface 22 which is in alignment with the sealing surface 24 and pertains to the inner leg of the respective sealing strip 21 at the end face. Furthermore, the angle-shaped sealing strip 113 has its end face 115 in sealing engagement with the end face 90 of the disc 4. As shown in FIG. 12, between the sealing strip 113 and the angle member 1 10 there is established a tight groove-spring connection. v

In FIG. 12 by means of crosses there are designated the surfaces which are formed by the described sealing strip combination and which are connected to each other. These surfaces engage the end face 90 of the disc 4 and thus form a closure for the working chambers which in every respect is sealed relative to the gap designated with e in FIG. 1.

The pressing of the slide ring segments 78 against the end I faces 90 of the discs 4 is affected on one hand by the oil pressure prevailing in the back of the slide ring segment and on the other hand by springs. I

FIG. 13 shows a spring 116 which is located at an area in the center between the end of the respective slide ring segment 78 and the center of the latter and which exerts an axial force upon the slide ring segment by means of an intermediate member 117 provided in a bore of the bearing ring 3. This slide ring segment has a grooving 118 engaged by an extension 119 of the intermediate member 117. The movement of the intermediate member 117 is axial direction outwardly is limited by a pin 120 located in the bearing ring 3 and engaging a recess 121 of the intermediate member.

At the end of the slide ring member 78, the end faces 90 of the discs 4 are subjected to pressure by the springs 88. The displacement stroke is limited by a bolt 122' provided in the cover member 83 which extends into recess 123' in the bearing ring 3 (FIG. 15).

Within the area of the radial central planes 80 of the sliding blocks, the angle-shaped sealing strips 113 are pressed in axial direction against the end face 90 of disc 4 and thus the angle members 110 and 101 and fie slide ring segments 78 are pressed onto the same surface by means of a helical spring 123 which rests against the extension 94 (FIG. 11).

The pressing of the slide ring segment 78 in radial direction against the bearing surface 104 of the groove 79 and the pressing of the angle-shaped sealing strip 113 toward the outside against the sealing surface 24 is effected by the abovementioned liquid pressure.

The displacement movement of the angle member 101 and of the slide ring segment 78 in axial outward direction is limited by a pin 125 on the angle member 110, said pin extending with play into a bore of the angle member 101.

For purposes of limiting the displacement movements of the angle-shaped sealing strip 113 under the influence of the helical spring 123 acting in axial direction and under the influence of the spring 124 acting in radial direction, there is provided a wire member 126 which is connected in a recess of the extension 94 to a leg 127 and has its other leg extending through a transverse bore 128 of the extension 94 into a groove 129 of the sealing strip 113 (FIG. 11, 18). This is illustrated in FIGS. 23-28 while the leaf spring 124 has been replaced by a helical spring 130. In this connection, it is assumed that the spring 123 acting in axial direction is considerably stronger than the spring 130 acting in radial direction. The line of action of the resultant of the forces exerted by the two springs is indicated in FIG. 25 with the reference numeral 131. The groove 129 extends transverse to the said line of action and in particular has an inner engaging surface 132 which is arranged at a right angle to the action line 131. Furthermore, groove 129 has a bulge 133 extending in the direction toward the spring 130.

FIGS. 27 and 28 illustrate the conditions which prevail prior to the respective disc 4 being mounted in its final position with regard to the housing 1. The sealing strip 130 is by the stronger spring 123 moved outwardly in axial direction out of the slot 124 of the extension 94 of sliding bushing 19 by the extent d. The engaging surface 132 will then engage the long leg of the wire member 126. In view of the inclined position of this engaging surface and the inherent effect of an inclined plane, the sealing strip 113 is in view of the axial force of spring 123 and against the thrust of the weaker spring 130 within the slot 134 moved inwardly. When the disc 4 engages the housing 1 in axial direction as shown by an arrow R in FIG. 27, between the annular bead, enlargement, or wavy annular projection 7 and the sealing strip 113 there is formed a radial slot 135 so that the axial introduction of the disc 4 brings about no sliding friction on the strip 113.

Only when during the complete insertion of the disc the end face 90 thereof engages the end face 115 of the sealing strip 113 and, consequently, the latter presses in axial direction into the slot 134, the sealing strip 113 will, by means of spring 130, be moved radially outwardly until it engages the inner circumferential surface 24 ofthe annular bead 7 During the axial displacement of the sealing strip 113, the inclined engaging surface 132 of groove 129 will be freed from the wire member As will be seen from FIG. 29, those slide ring segments 140 which seal the gaps e with regard to each other, in other words, which serve for sealing between the working chambers on different sides of the housing, may in distinction from slide ring segments 78 be curved concentrically with regard to the cylindrical central member 2 of the rotor. The axis of curvature thus coincides with the axis of rotation 5 of the rotor. In order to assure that, nevertheless, the sliding ring segments 140 in FIG. 29 will not dig into the end faces 90 of the discs 4, the said sliding ring segments have those end faces thereof which face the end faces 90 provided with recesses 141 which may for instance be milled thereinto. These recesses 141 are so designed that every annular segment 140 will at its marginal area facing said axis of curvature retain a narrow engaging surface 142 which is connected over the entire circumference while between the recesses 141 weblike engaging surfaces 143 remain. This design of the engaging surfaces of the slide ring 51, 52 of the slide ring segm giisi according to FIG. 9. In this way, between the slide ring segments 140 and the end faces of discs 4 an oil film is formed which prevents a premature wear during the sliding of the end faces 90 on the slide ring segments 140. The slide ring segments 140 are located in grooves 144 which are concentrically provided in the bearing rings 3. The slide ring segments 140 extend over almost a fourth of the circumference. The gaps 145 between each two slide ring segments 140 are bridged by angular cover members 146 which act precisely in the same manner as the cover members 42 of FIGS. 4 and 5. In order to assure that the slide ring segments 140 will not be displaced tangentially in the grooves 144, they are in the vicinity of their central portion each provided with two elevations 147 which fit into radial slots 148 on the end faces of the extensions 94 of the sliding block bushings 19. FIG. 29 shows the individual components of a similar sealing strip combination as illustrated in FIGS. "-19. According to this lastmentioned combination, an angular sealing strip 150 is guided in a longitudinal slot 149 of the slide ring bushing 19 and in its extension 94. Instead of the separate angle members 101 and of the embodiment of FIGS. 11 and 12, an angle member 151 is provided which on one hand radially displaceably communicates in a sealing connection with the angular sealing strip 150 and on the other hand tightly surrounds the slide ring segment 140. Springs 123 and are also in this instance provided for pressing the angle-shaped sealing strips 150 in axial and radial direction.

It is, of course, to be understood that the present invention is, by no means, limited to the particular constructions shown in the drawings but also comprises any modifications withi v the scope of the appended claims.

What we claim is:

1. In a rotary fluid displacement machine; a housing having a cylindrical cavity, a cylindrical rotor journaled in said cavity and including end discs secured thereto and overlying opposite ends of said housing, annular projections having coaxial cylindrical inner and outer surfaces formed on the axially inner sides of said end discs, undulating cam surfaces formed on the axially inner ends of said projections forming therebetween and undulating path of constant axial dimension, annular grooves formed in the ends of said housing closely receiving said annular projections, axial bores in said housing in the radial range of said annular grooves, sliding blocks in said bores having their opposite ends in engagement with said cam surfaces and dividing the said annular grooves into working chambers, first and second passage means in said housing connecting alternate ones of said working chambers at each end of said housing together while the said working chambers axially opposite each other are connected to different ones of said passage means, and sealing means sealing against leakage from said working chambers through the gaps between said housing and rotor toward the outside of the 5 housing and between working chambers, said sealing means comprising ring elements disposed between said housing and said rotor on both the radially inner and radially outer sides of said annular projections, each ring element comprising segments in end to end relation,- each segment extending from the radial plane of a respective sliding block in both directions to just short of the midpoint of the working chambers on both sides of the respective said sliding block and having surfaces sealingly engaging the rotor and the housing, and cover members bridging the gap between adjacent ends of adjacent ones of said segments and having surfaces sealingly engaging said segments and said rotor and said housing.

2. A machine according to claim 1, in which said segments are mounted with both axial and radial play in grooves provided therefor in the ends of said housing, and angle means engaging each segment in about the center of the length thereof, each angle means having surfaces sealingly engaging sides of the respective segment which do not engage the rotor and housing and also having surfaces sealingly engaging the rotor segments is thus similar to that of the engaging surfaces 75 and housing.

ill

3. A machine according to claim 2, in which each sliding block has a diametral slot in each end, a seal strip in each slot engaging the adjacent cam surface, each said seal strip having radially inner and radially outer axial end portions, and means slidably sealing each of the radially inner and outer surfaces of the said axial end portions to respective adjacent ones of said angle means.

t. A machine according to claim 3, in which each said angle means on the radially outer side of each said projection comprises an axial portion which is sealingly and slidably engaged by the radially outer surface of the outer one of said axial end portions of the adjacent seal strip.

5. A machine according to claim 3, in which an axial seal member is provided slidably sealingly engaging the radially inner side of the inner one of said axial end portion of each said seal strip and is also sealingly connected to the respective adjacent angle means.

6. A machine according to claim 3, which includes spring means biasing said segments outwardly in their respective grooves toward said rotor, and lost motion means connecting the segments to the housing and preventing the segments from leaving said grooves under the influence of said spring means.

7. A machine according to claim 6, in which the said segments sealing between the housing and the rotor toward the outside engage the outer periphery of said annular projections on said end discs.

8. A machine according to claim 7, in which the segments sealing between the housing and the rotor toward the outside form a circular seal ring, each segment having an upstanding rib on the radially outer side near the center, and said housing having notches in each end to receive respective ones of said ribs whereby circumferential movement of the pertaining segments in their grooves is prevented.

9. A machine according to claim 7, in which bushings are fixed in said bores and slidably receive said sliding blocks, each bushing having an extension on each end thereof on the radially inner and radially outer sides projecting toward but terminating short of the planes of the inner sides of said end discs, and disposed on radially opposite sides of said annular projections on said end discs, axial slots in said extensions in planes passing through the axis of the respective sliding block and through the axis of rotation of said rotor, said means effecting sliding sealing engagement between said angle means and said axial portions of said seal strips including means slidably sealingly mounted in said slots.

10. A machine according to claim l, in which said angle means pertaining to the segments on the radially outer side of said annular projections have integral therewith an axial extension which slidably sealingly engages the radially outer surface of the outer one of the axial portions of the adjacent said seal strip.

11. A machine according to claim llll, in which a yoltelilte seal member is provided sealingly engaging the radially outer side of each angle means pertaining to the segments on the radially outer side of said annular projections, each said yokelike member being disposed in the slot in the radially outer extension of the pertaining bushing and sealingly engaging the respective bore for the said bushing.

12. A machine according to claim 3, in which the means slidably sealing the angle means for the said segments on the radially inner side of said annular projections to the radially inner surfaces of the inner axial portions of the adjacent sealing strips comprises yokelike seal member having an axial portion in the said slot in the radially inner extension of the respective said bushing, said yokelike seal member having an end part with surfaces sealingly engaging the rotor and the adjacent angle means, and a further seal element in the said slot sealingly engaging said end part of said yokelike seal member and also sealingly engaging the respective angle means.

13. A machine according to claim ill, in which said yokelilte sealing member and the respective angle means are spring urged apart in the radial direction and are provided on their ends adjacent the rotor with interfitting axial tongue and groove seal means.

M. A machine according to aaim 12, in which said yokelike sealing member and the respective angle means are spring urged apart in the radial direction and are provided on their ends adjacent the rotor with interfitting axial tongue and groove seal means.

15. A machine according to claim 2, which includes a seal element engaging the side of each angle means opposite the rotor and also sealingly engages the said rotor, each seal element sealingly engaging the surface of the adjacent bore in the housing, spring means between each seal element and the respective angle means urging them radially apart, and other spring means between the seal element and the housing urging the seal element and pertaining angle means toward the rotor.

16. A machine according to claim 1, in which each said cover member for the segments on the radially outer side of said annular projections sealingly engages the rotor and the adjacent cylindrical surface of the respective annular projections and the sides of the respective segments opposite the rotor, the ends of said segments having notches on their radially outer sides for receiving said cover member and having coplanar bottom surfaces, said cover member having a planer bottom surface sealingly engaging the said bottom surfaces of said notches.

17. A machine according to claim 16, in which a spring is provided urging each said cover member radially inwardly toward the respective segments.

18. A machine according to claim 17, which includes further springs engaging the outsides of said segments and urging them radially inwardly in the circumferential region between said cover members and the center of the segments.

19. A machine according to claim 18, in which each said segment on the side toward the adjacent cylindrical surface of the pertaining annular projection is provided with pockets which define a continuous annular surface with spaced axial webs.

20. A machine according to claim 19, in which bore means is provided in each segment leading from at least one said pocket thereof to the radially outer side of the said segment.

21. A machine according to claim 19, in which said pockets are open at their axially inner ends and are closed at their axially outer ends by said annular surface, and notchlike recesses in the inner side of each segment opening toward the axially outer side of the respective segment.

22. A machine according to claim 2, in which the grooves for the segments on the radially inner sides of said annular projections consists of sections each of which has the same radius of curvature substantially greater than the distance of the groove sections from the axis of rotation of said rotor.

23. A machine according to claim 3, in which the said extensions on the radially inner sides of said bushings are nested in rounded recesses provided therefor in said housing.

24. A machine according to claim 23, in which a seal member is provided for sealing the radial gap between each said extension on the radially inner side of each bushing and the surface of the respective rounded recess in the housing, each seal member sealingly engaging opposite ends of the adjacent angle means and the rotor at opposite ends of said angle means and also sealingly engaging the circumferential surfaces of said extension and said recess.

25. A machine according to claim 3, which includes an axial recess in said housing behind each said cover member which bridges between the adjacent ends of adjacent ones of the segments on the radially inner sides of said annular projections, each said cover member extending sealingly into the respective said recess and being biased outwardly of the recess toward the rotor.

26. A machine according to claim 25, in which the end of said cover member adjacent said rotor is provided with notch means and sealingly receives the ends of said segments in said notch means.

27. A machine according to claim 15, which includes a pin in the housing extending perpendicularly to each seal element, each seal element having a groove therein into which the respective pin extends, each groove being wider than the 13 4 diameter of the respective iii? and being elongated in a said groove nearest the resnEFt iV end disc has an enlarged redirection perpendicular to the resultant of the forces exerted g n th lcinon id l element b h pertaining id spring means and 29. A machine according to claim 27, m which said pin is in other spring means, the form of an angled off leg of a resilient wire member.

28. A machine according to claim 27, in which that end of 5 

1. In a rotary fluid displacement machine; a housing having a cylindrical cavity, a cylindrical rotor journaled in said cavity and including end discs secured thereto and overlying opposite ends of said housing, annular projections having coaxial cylindrical inner and outer surfaces formed on the axially inner sides of said end discs, undulating cam surfaces formed on the axially inner ends of said projections forming therebetween and undulating path of constant axial dimension, annular grooves formed in the ends of said housing closely receiving said annular projections, axial bores in said housing in the radial range of said annular grooves, sliding blocks in said bores having their opposite ends in engagement with said cam surfaces and dividing the said annular grooves into working chambers, first and second passage means in said housing connecting alternate ones of said working chambers at each end of said housing together while the said working chambers axially opposite each other are connected to different ones of said passage means, and sealing means sealing against leakage from said working chambers through the gaps between said housing and rotor toward the outside of the housing and between working chambers, said sealing means comprising ring elements disposed between said housing and said rotor on both the radially inner and radially outer sides of said annular projections, each ring element comprising segments in end to end relation, each segment extending from the radial plane of a respective sliding block in both directions to just short of the midpoint of the working chambers on both sides of the respective said sliding block and having surfaces sealingly engaging the rotor and the housing, and cover members bridging the gap between adjacent ends of adjacent ones of said segments and having surfaces sealingly engaging said segments and said rotor and said housing.
 2. A machine according to claim 1, in which said segments are mounted with both axial and radial play in grooves provided therefor in the ends of said housing, and angle means engaging each segment in about the center of the length thereof, each angle means having surfaces sealingly engaging sides of the respective segment which do not engage the rotor and housing and also having surfaces sealingly engaging The rotor and housing.
 3. A machine according to claim 2, in which each sliding block has a diametral slot in each end, a seal strip in each slot engaging the adjacent cam surface, each said seal strip having radially inner and radially outer axial end portions, and means slidably sealing each of the radially inner and outer surfaces of the said axial end portions to respective adjacent ones of said angle means.
 4. A machine according to claim 3, in which each said angle means on the radially outer side of each said projection comprises an axial portion which is sealingly and slidably engaged by the radially outer surface of the outer one of said axial end portions of the adjacent seal strip.
 5. A machine according to claim 3, in which an axial seal member is provided slidably sealingly engaging the radially inner side of the inner one of said axial end portion of each said seal strip and is also sealingly connected to the respective adjacent angle means.
 6. A machine according to claim 3, which includes spring means biasing said segments outwardly in their respective grooves toward said rotor, and lost motion means connecting the segments to the housing and preventing the segments from leaving said grooves under the influence of said spring means.
 7. A machine according to claim 6, in which the said segments sealing between the housing and the rotor toward the outside engage the outer periphery of said annular projections on said end discs.
 8. A machine according to claim 7, in which the segments sealing between the housing and the rotor toward the outside form a circular seal ring, each segment having an upstanding rib on the radially outer side near the center, and said housing having notches in each end to receive respective ones of said ribs whereby circumferential movement of the pertaining segments in their grooves is prevented.
 9. A machine according to claim 7, in which bushings are fixed in said bores and slidably receive said sliding blocks, each bushing having an extension on each end thereof on the radially inner and radially outer sides projecting toward but terminating short of the planes of the inner sides of said end discs, and disposed on radially opposite sides of said annular projections on said end discs, axial slots in said extensions in planes passing through the axis of the respective sliding block and through the axis of rotation of said rotor, said means effecting sliding sealing engagement between said angle means and said axial portions of said seal strips including means slidably sealingly mounted in said slots.
 10. A machine according to claim 4, in which said angle means pertaining to the segments on the radially outer side of said annular projections have integral therewith an axial extension which slidably sealingly engages the radially outer surface of the outer one of the axial portions of the adjacent said seal strip.
 11. A machine according to claim 10, in which a yokelike seal member is provided sealingly engaging the radially outer side of each angle means pertaining to the segments on the radially outer side of said annular projections, each said yokelike member being disposed in the slot in the radially outer extension of the pertaining bushing and sealingly engaging the respective bore for the said bushing.
 12. A machine according to claim 3, in which the means slidably sealing the angle means for the said segments on the radially inner side of said annular projections to the radially inner surfaces of the inner axial portions of the adjacent sealing strips comprises yokelike seal member having an axial portion in the said slot in the radially inner extension of the respective said bushing, said yokelike seal member having an end part with surfaces sealingly engaging the rotor and the adjacent angle means, and a further seal element in the said slot sealingly engaging said end part of said yokelike seal member and also sealingly engaging the respective angle means.
 13. A machine according to clAim 11, in which said yokelike sealing member and the respective angle means are spring urged apart in the radial direction and are provided on their ends adjacent the rotor with interfitting axial tongue and groove seal means.
 14. A machine according to claim 12, in which said yokelike sealing member and the respective angle means are spring urged apart in the radial direction and are provided on their ends adjacent the rotor with interfitting axial tongue and groove seal means.
 15. A machine according to claim 2, which includes a seal element engaging the side of each angle means opposite the rotor and also sealingly engages the said rotor, each seal element sealingly engaging the surface of the adjacent bore in the housing, spring means between each seal element and the respective angle means urging them radially apart, and other spring means between the seal element and the housing urging the seal element and pertaining angle means toward the rotor.
 16. A machine according to claim 1, in which each said cover member for the segments on the radially outer side of said annular projections sealingly engages the rotor and the adjacent cylindrical surface of the respective annular projections and the sides of the respective segments opposite the rotor, the ends of said segments having notches on their radially outer sides for receiving said cover member and having coplanar bottom surfaces, said cover member having a planer bottom surface sealingly engaging the said bottom surfaces of said notches.
 17. A machine according to claim 16, in which a spring is provided urging each said cover member radially inwardly toward the respective segments.
 18. A machine according to claim 17, which includes further springs engaging the outsides of said segments and urging them radially inwardly in the circumferential region between said cover members and the center of the segments.
 19. A machine according to claim 18, in which each said segment on the side toward the adjacent cylindrical surface of the pertaining annular projection is provided with pockets which define a continuous annular surface with spaced axial webs.
 20. A machine according to claim 19, in which bore means is provided in each segment leading from at least one said pocket thereof to the radially outer side of the said segment.
 21. A machine according to claim 19, in which said pockets are open at their axially inner ends and are closed at their axially outer ends by said annular surface, and notchlike recesses in the inner side of each segment opening toward the axially outer side of the respective segment.
 22. A machine according to claim 2, in which the grooves for the segments on the radially inner sides of said annular projections consists of sections each of which has the same radius of curvature substantially greater than the distance of the groove sections from the axis of rotation of said rotor.
 23. A machine according to claim 3, in which the said extensions on the radially inner sides of said bushings are nested in rounded recesses provided therefor in said housing.
 24. A machine according to claim 23, in which a seal member is provided for sealing the radial gap between each said extension on the radially inner side of each bushing and the surface of the respective rounded recess in the housing, each seal member sealingly engaging opposite ends of the adjacent angle means and the rotor at opposite ends of said angle means and also sealingly engaging the circumferential surfaces of said extension and said recess.
 25. A machine according to claim 3, which includes an axial recess in said housing behind each said cover member which bridges between the adjacent ends of adjacent ones of the segments on the radially inner sides of said annular projections, each said cover member extending sealingly into the respective said recess and being biased outwardly of the recess toward the rotor.
 26. A machine according to claim 25, in which the end of said cover member adjacent said roTor is provided with notch means and sealingly receives the ends of said segments in said notch means.
 27. A machine according to claim 15, which includes a pin in the housing extending perpendicularly to each seal element, each seal element having a groove therein into which the respective pin extends, each groove being wider than the diameter of the respective pin and being elongated in a direction perpendicular to the resultant of the forces exerted on said seal element by the pertaining said spring means and other spring means.
 28. A machine according to claim 27, in which that end of said groove nearest the respective end disc has an enlarged region therein.
 29. A machine according to claim 27, in which said pin is in the form of an angled off leg of a resilient wire member. 